Electronic musical instrument



April 1966 R. H. PETERSON 3,247,308

ELECTRONIC MUSICAL INSTRUMENT Filed Jan. 25, 1961 4 Sheets-Sheet 1 RANDOM j' 34 NOISE 32 a T \-;RELAY P 2235 ECA have PULSE IT FILTERS GEN. 3 I37 h h Hr I l AMP 45 J 4? su F 268 4 20 4 nwnuwnw v QELAY" *1 GEN E 55 56) 6) RELAY m'ExToR.

RICHARD H.PETER5ON BY W 3i ATTORNE\ April 1966 R. H. PETERSON 3,247,308

ELECTRONIC MUSICAL INSTRUMENT Filed Jan. 25, 1961 4 Sheets-Sheet 2 Q0 b86 Rqz TIME FlC1.7

INVENTOR. RICHARD H. PETERSON ATTCHZNEY April 1966 R. H. PETERSON 3,247,308

ELECTRONIC MUSICAL INSTRUMENT Filed Jan. 25, 1961 4 Sheets-Sheet 5 68\ 260 t f 7% I I PULSE I I GEN. l EJZI 26 I I E.C.A. I EIasz I FIVE I FILTERS T TO l T2ANsDuCERS ADJUSTABLE DELAY RELAY I l 61. IO

INVENTOR.

RICHARD H. DE TERSON ATTORNEY April 19, 1966 R. H. PETERSON ELECTRONIC MUSICAL INSTRUMENT I GEN. 60 4 Fl Cl. 15

4 Sheets-Sheet 4.

I"; P54 I T L 356 322i: 324 344 E 348? 542 333 346 INVENTOR.

RHZHARD H. PETERSON ATTORN EY United States Patent C) 3,247,308 ELECTRDNIC MUSICAL INSTRUMENT Richard H. Peterson, 10108 Harnew Road E., Oaklawn, Ill. Filed Jan. 25, 1961, Ser. No. 84,951 4 Claims. (Cl. 84-1.17)

My invention relates to electronic musical instruments and includes among its objects and advantages; the production of a variety of unpitched sound effects, many of which are percussive; the production of sound effects in automatically executed repetitive time sequences; and the convenient control of both of the above mentioned functions, without requiring the player to master difficult special techniques or skills and with substantially negligible interruption or impairment of the players ability to continue the normal playing functions.

Most musical instruments provide tones having frequencies corresponding to the notes of the musical scale. However, there is a large group of instruments that are generally used for rhythmic accompaniment to other instruments wherein the rhythmic accompaniment consists of sound or frequently series of sounds that may contain a great many frequencies but that have no clearly defined pitch characteristics. Such instruments include drums, cymbals, triangles, m-aracas, Wood blocks, tambourines, and many others. Some of these instruments, such as bongo drums, and maracas, usually produce random noise more or less concentrated over a predetermined range of frequencies and in a sense may be considered semi-pitched. These sounds are included in the meaning of the word unpitched as used herein. Both semi-pitched and unpitched sounds are suitable for the primary beat, or ictus, in ordinary music, as well as for the two secondary beats in waltz time, or the three secondary beats in A, time.

While not necessarily limited to a particular application, the features of this application may advantageously be employed in connection with musical instruments of the organ type.

A few decades ago, pipe organs were very commonly used to provide accompaniment to the silent motion pictures of the day. These entertainment organs were highly orchestral in character and in fact one large manufacturer called its organs unit orchestras. These instruments commonly employed a large variety of percussive instruments of the type described. The actual acoustic instruments were generally employed and were provided with suitable heaters or shakers that were controlled by magnets or pneumatics and were operated in response to a depression of a suitable key on the organ.

In order that highly orchestral effects could be created, certain other schemes were developed to allow the organist more flexibility in the use of these effects. One such device was known as the second touch or double touch. Where double touch was employed, the playing keys of the organ were each associated with two sets of contacts, one of which was operated in the usual manner to control most of the tones of the organ, while the second group of contacts controlled by each key was only actuated upon the exertion of a considerable amount of additional pressure on the playing key to control the other effects. These and similar means enabled the organist to produce remarkably orchestral sounds but the technique for playing such instruments was not easily acquired.

Currently, large numbers of electronic organs are being produced for entertainment purposes. It is one purpose of this invention to provide means and apparatus for creating rhythmic effects such as those described in connection with electronic organs. It is a further object of operator can provide a wide variety of unpitched percussive effects and at the same time to control such effects much greater facility than has been heretofore poss1 e.

In the accompanying drawings:

FIGURE 1 is a general block diagram of an installation according to the invention;

FIGURE 2 is a schematic diagram of a random noise generator;

FIGURE 3 is a schematic diagram of a different random noise generator;

FIGURE 4 is a schematic diagram of a preferred envelope control apparatus;

FIGURE 5 is a time-potential curve for the envelope I secured with equipment according to FIGURE 4;

FIGURE 6 is a partly structural section of means for generating a current pulse;

FIGURE 7 is a time-potential curve of the pulse from equipment according to FIGURE 6;

FIGURE 8 is a time-potential curve of a logarithmic decrement timer according to FIGURE 10;

FIGURE 9 is a schematic diagram of a multiple adjustable filter unit;

FIGURE 10 is a partial schematic diagram of the triggering and timing circuits;

FIGURE 11 is a perspective side elevation of a conventional console;

FIGURE 12 is a schematic diagram of a modification of the first key controlled relay;

FIGURE 13 is a schematic diagram of a normally inactive noise generator adapted to define its own envelope;

FIGURE 14 is a schematic diagram of a normally inactive generator for semi-pitched noise;

FIGURE 15 is a plan view of mechanical control equipment for controlling bursts of signal; and

FIGURES 16 and 17 are sections on lines 1616 and 1717 of FIGURE 15.

In the embodiment selected to illustrate the invention and referring first to FIGURE 11, the console 10 may be conventional, and comprises a box-like frame carrying a solo manual 12, and an accompaniment manual 14. A set of bass pedals 16 projects forward to a position convenient for the feet of the player seated on a bench 18.

The conventional pitched tone generator 20, and part or all of the units diagrammed in FIGURE 1 may be housed in the console 10.

Stops are provided, usually in the nature of simple on-and-olf switches, for enabling the player to select all the varieties of sound effects within the gamut of the instrument. Those associated with the manuals 12 and 14 are grouped at 21 and 23, adjacent the manuals they affect. Those associated with the pedals are usually above the manual 12, as at 25, leaving a space at 27 available for independent and irrelevant instrumentalities, such as signal or voice equipment for communication with the minister or others, control connections for a tape recorder, etc.

In FIGURE 1, I have indicated a cable 15 connecting the generator 20 and the manual 14, as well as a similar cable 17 connecting the generator 20 and the pedal clavier 16. It will be understood that each of these cables usually contains as many individual wires as there are keys on the clavier to which it is connected, and that these wires are again separated in the pitched tone generator to be connected to activate the individual oscillators of the generator. As these connections are both conventional and complicated and, per se, form no part of the present invention, this disclosure has not been encumbered with those details.

Referring now to FIGURE 1, the random noise generator 19, delivers an electrical signal including a very large number of unrelated audio-frequencies. If this: tone signal were to be fed into an amplifier and loud--' speaker it would have the general character of a hiss.. The output signal from this random noise generator may be connected to five channels leading to five envelope controlling apparatuses 22, 24, 26, 28, and 30. Each of these might be likened to a gate which controls the intensity of the signal transmitted therethrough, and this: envelope control apparatus may be a variable gain amplifier or a variable attenuator. Each envelope controlling apparatus is provided with a terminal 32, 34, 36, 38 or 40, where the signal appears with the intensity determined by the gate. After passing through the envelope control apparatus, the signal may be fed to an appropriate filter unit 42, 43, 44, 45 or 46. These filters may include lowpass filters, highpass filters, bandpass filters, or resonant filters, depending upon the sound to be produced. The output of these filters goes to the am-- plifier 50 and the loudspeaker 52.

Associated with the claviers 14 and 16 are relays 54 (see FIG. 10) and 56, respectively, each connected toits clavier in such a way that the relay will be operated in response to manipulation of any key of its associated clavier. Relay 54 has a potential source 55 and relay 56 has a potential source 5%. Relay 54 is connected to deliver potential to a pulse generator 60 (see FIG. 1), which activates a timer 62 (see FIGS. 8 and 10) which activates two adjustable time delay relays 64 and 66 (see FIG. 1). Relay 56 is connected similarly through pulse generator 61, and timer 63 to three adjustable time delay relays 68, 70 and 72. Each adjustable time delay relay, in combination with its timer, interposes an adjustably predetermined amount of time before its output terminal is energized. The output terminals of the adjustable time delay relays are connected to pulse generators 74, 76, 78, 80 and 82. Each pulse generator, when energized, delivers a single pulse of energy to its associated envelope controlling apparatus 22, 24, 26, 28 or 30. This pulse, which may be of any pre-selected duration, controls the operation of the envelopecontrolling apparatus in such manner that a signal from the random noise generator is keyed with a percussive envelope characteristic and the pulse of the random noise signal is then fed through the filter and thence through the amplifier and loudspeaker and is heard as an unpitched percussive sound. the filtering need not necessarily be done after the envelope is formed.

The operation of any key on the manual clavier 14 results in the production of two different percussive sounds, which sounds may be heard in a timed sequence depending upon the selected time delay of the relays 64 and 66. In a similar manner the operation of any key on the pedal clavier 16 results in the sounding of a sequence of three unpitched percussive sounds corresponding to the random noise signal as modified by the filters 44, 45 and 46, and characterized by the particular envelope characteristics afforded by each of the envelope controlling means 26, 28 and 30. It will be obvious that the player, by suitable adjustment of the adjustable time delay relays 64, 66, 68, 70 and 72, and by suitable manipulation of the manual and pedal claviers, may arrange to produce a wide variety of rhythmic unpitched sounds and the single playing manipulation of depressing a single key results in the pitched note corresponding to that key, plus an entire train, or timed sequence, of additional sounds.

If, for instance, the player desires to provide a rhythmic unpitched accompaniment for a waltz, he may choose to set the adjustable time delay relays such that the relay 68 would provide zero time delay, relay 70 would It will be obvious that be adjusted to produce a time delay of approximately I second, and relay 66 would be adjusted to produce a time delay of /2 second. The adjustable filter 44 might then be adjusted to provide a thump corresponding to that of a bass drum and the adjustable filters 45 and 46 might be adjusted to produce sounds corresponding to those produced by a wire brush acting upon a cymbal. Now, in response to the depression of any pedal key, the instrument will produce a pitched sound corresponding to the pedal played and instantly upon playing the key will produce a bass drum sound followed by two brush cymbal after-beats. At the same time, if it is so desired, the time delay relays 64 and 66 and the adjustable filters 42 and 44 can be set for the production of two after-beats corresponding to two different instruments which may for example, in the case illustrated, usefully be two maracas producing semipitohed noises.

The shape of the envelope may be made adjustable in various ways. For example the duration of the pulse delivered to the control can be increased, which will keep the sound on a plateau as long as the pulse endures, or the duration of the decay may be varied. With the filter adjustments and envelope adjustments combined, the variety of the repertory available to a single performer may come close to the best that a (full orchestra can provide.

RANDOM NOISE GENERATION In FIGURE 2 a single diode 84 isused as the source of noise. A power source 86 is simply connected in series with the diode 84 and a load resistor 88. If the diode is connected in the direction to resist the flow of current from the source 88, slight leakage through the diode due to the inherent characteristics of the diode, will have a very wide distribution of energy throughout the complete audio spectrum. This energy can be utilized for the purpose intended by simply connecting it to the rest of the circuit through the DO. blocking capacitor 90. The terminal 92 is the terminal of the generator 19 in FIGURE 1. The diode 84 may be any one of a variety of types but is preferably of the semi-conductor variety such as the commonly employed silicon, germanium or copper oxide units.

Ainother noise generator is shown in FIGURE 3. Transistors 9 4 and 95 are connected as a conventional two-stage amplifier of the common emitter configuration except that there is no signal connected to the input of the amplifier. Instead, the two transistors merely amplify the noise generated in the input circuit of the transistor 94. The circuit is adjusted to have a very high gain and the resistor 96- is selected such that the transistor 94 will provide a maximum amount of noise. Typical values for the components may be as follows: resistor 97, 15,000 ohms, resistor 98, 82,000 ohms, resistor 99, 200,000 ohms, resistor 100, 300 ohms, capacitor 102, 5 microfarads, capacitor 104, .02 microfarad, capacitor 106, 5 microfarads, the transistors may be of the type known as RCA 2N 109. This circuit produces random noise of much greater amplitude than that of FIGURE 2.

Referring now to FIGURE 4, the envelope controlling apparatus shown is of the attenuator type. The degree of attenuation is a tunction of the light ttalling upon the sensitive surface of a photo-resistor 108. This photoresistor may be of any suitable type, such as the cadmium sulfide or cadmium selenide varieties. The complete attenuator circuit consists of the resistors 110, 112 and 114, in addition .to the photo-resistor .108 and the lamp 116, which two components are sealed in a light tight container 118. The resistance of the photo-resistor 108 and the resistance of resistor 112 form an audio-afrequency voltage divider, and if a signal is impressed between the input terminal and ground at 122, the output signal will be according to the formula; signal in over signal out equals R 110 plus R 108 plus R 112 over R 112. This formula is correct, assuming that the impedance presented by the following external circuitry across terminals 122 and 124 is large, and that of resistor 110 relatively negligible.

Since the impedance of the photo-resistor 108 is variable over ratios of several million to one, depending upon the illumination of its surface, it is a simple matter to adjust the i-mpedances in the circuit to produce attenuation factors in excess of 90 decibels. The resistors 110 and 114 are primarily for the purpose of isolating the attenuator from the input and output circuits.

The potential applied to the lamp 116 determines its brightness, and thereby the illumination of the photoresistor 108 and thereby the attenuation ratio of the attenuator. It is interesting that if a pulse of voltage is applied to terminal 121, the attenuation with respect to time will not exactly follow the wave form of the pulse, but will be influenced by the thermal inertia of the filament of the lamp 116 and also by the characteristics of the photo-resistor, the resistance of which does not respond exactly simultaneously to changes in illumination. Cadmium sulfide cells in particular have a time lag in their response upon the removal of illumination. These two factors combine to cause the attenuator described to have advantageous characteristics for producing percussive envelope characteristics.

FIGURE 7 is a time-potential curve indicating the characteristics of a pulse from a pulse generator according to FIGURE 6. FIGURE 5 is a time-potential curve of the envelope of the resulting pulse delivered 'by the envelope control of FIGURE 4. The rising curve 128 is delayed chiefly by the thermal inertia of the filament, and the falling curve 125 is determined chiefly by the photo resistor 108. The intermediate plateau 127 represents the continuation of full potential to the end of the pulse from the pulse generator.

There are several methods by which the attenuation versus time characteristics of the attenuator can be varied over a wide range. One of these methods is to the impedances 110 and/or 112. Another method is to connect a suitable capacitor across the lamp 116 so that energy stored in the capacitor may cause the continuation of current in the lamp for a period of time after the pulse has been removed from terminal 121. I have indicated in FIGURE 4 a switch 128 arranged to connect either of two capacitors 130 and 132 to the circuit for this purpose.

THE ADJUSTABLE FILTERS FIGURE 9 shows a filter unit that may be employed with the other features of the invention. The filter unit 42, etc., is illustrated as a group of five separate filters, each having certain characteristics and arranged so that filters can be used either singly or in combination by means of stop switches 133. For convenience, the input terminal of the filter equipment has been designated as 134 and the output as 136. The five switches, 133 are not shown in FIGURE 1 as they are part of the filter unit itself. These switches connect the input signal to any one or more of the five paths through which the signal can be conducted to the output terminal 136.

. The first path consists simply of the resistor 148 which serves to transmit the signal unaflected as far as harmonic structure is concerned, but that controls the amplitude of the signal transmitted. The second path is through resistors 150 and 152, which have a capacitor 154 connected from their common junction to ground. This forms a conventional low pass filter which allows the lower frequencies of the audio spectrum to be transmitted, and attenuates the higher frequencies. The third signal path is through capacitors 156 and 158, which have a resistor 160 connected from the junction of the two capacitors to ground. This forms a high pass filter which transmits the higher frequencies of the audio spectrum with greater facility than it transmits the lower components. The fourth path consists of the resistors 161 and 163 which have a tuned circuit consisting of inductor .162 and capacitor 164 connected between ground and the junction of the two resistors. This forms a tuned circuit, or formant, filter, which emphasizes those frequencies in the audio spectrum near the resonant frequency determined by the inductor 162 and capacitor 164. The fifth path consists of the circuit including resistors and 172 and the inductors 174 and 176 and the capacitors 178, 180 and 182. This is what is known as'a band pass circuit and it will pass a band of frequencies with fairly uniform intensity and other frequencies above and below this band will be attenuated sharply. The frequencies that are included within the band pass region are determined by the constants of the inductors and capacitors.

By a suitable selection of one or more of the switches 133 the player may select any one of a wide variety of tonal effects which, when delivered to terminal 136, and thence through the amplifier 50 and loudspeaker 52, will correspond to a great many of the percussive sounds produced by conventional acoustic instruments, as well as others that have no orchestral counterparts.

The filters themselves, per se, form no part of this invention, and many different types of filters may be employed to produce various desired results. For example, some or all of the resistors, capacitors and inductors may be made individually variable, so that the characteristics of the filter networks can be endlessly varied.

The amplifier 50 and the loudspeaker 52 may be conventional. I prefer to provide the amplifier with conventional means for adjusting its volume or tone quality as indicated at 49 and 51. In some instances, 1 may use the same amplifier and loudspeaker that is used for the reproduction of the ordinary organ tones. In other cases, I prefer to provide a plurality of amplifiers and loudspeakers, as for example, a separate amplifier and loudspeaker for each envelope controlling apparatus.

In FIGURE 1 I have indicated a separate amplifier and loudspeaker unit -135 for filter 42, and a stop switch at 137 for connecting filter 42 to either amplifier 52 or 135. Filter 46 is also provided with another separate amplifier-loudspeaker unit 139 and stop switch 141.

PULSE GENERATOR Referring now to FIGURE 6, I have indicated means for providing a pulse of energy to trigger the envelope controlling apparatus for the random noise signal.

FIGURE 1 indicates seven such pulse generators, two for triggering the timers 62 and 63, and five for triggering the envelope controls 22, 24, 26, 28, 30.

The energizing coil 184 is wound around a piece of non magnetic tubing 190. Inside the tube is a ferromagnetic armature 192. The armature is connected to a contact plate 194 and with the coil de-energized it will rest in full line position. When the coil is energized, the armature will move up and come to final rest in the position indicated at 198. However, due to its inertia, upon initial actuation it will overshoot this position and rise to some such level as indicated at .196 and momentarily cause the contact plate 194 to be brought into contact with the contacts 186 and 188.

I have found that there is a natural tendency for such i an armature to oscillate back and forth and tend to supply two or three impulses instead of the desired single one. I have found that this can be prevented by the soft iron damping washer 200 placed around the upper end of the coil. This causes the magnetic field to assume a configuration that allows the armature to overshoot once, but to substantially prevent downward movement below the position 198 as long as the coil is energized. Of course, when the energizing current is Withdrawn the parts drop back to full line position. A source of power 206 is connected to the contact 188. Energizing the magnet coil will cause a mechanical action that results in a single pulse of voltage from the source 206 being,

delivered to the terminal 186-.

A limit stop 208 defines the lowest level to which terminal 186 can descend. This stop may be raised or lowered by the adjustment knob 212, to decrease or increase the portion of the path of disc 194' during which current can flow. t r

' The pulse generators 74, 7 6, 78, 80, and 82, each need a potential source, indicated at 75,. in FIGURE 1.

INITIATION AND TIMING APPARATUS In FIGURE 10 the contacts 214 are operated by the keys of the clavier 14 (see FIG. 1) and receive potential from the source 216 through bus bar 217. When a key is depressed, bus bar 218 deliverspotential to coil 219 of relay 56, and conductor 220 delivers the potential of source 58 to pulse generator 61, which delivers a momentary pulse to the timer 63.

In timer 63 the pulse received raises the potential at point 222 to the full value of source 223, while some cur rent flows through the adjustable resistor 224, and shunt capacitor 226 picks up a full charge. As soon as the pulse'is over, point 222 will return to ground potential gradually as the capacitor discharges, chiefly through re-' sistor 224. In FIGURE 8 I have indicated the rise of point 222 to full potential at 226; its continuance'at that level to 228 represents the time duration of the pulse from generator 61. The logarithmic decrement curve 230 represents its gradual return to the original potential.

It will be obvious that adjustment of resistor 224 may vary the horizontal time scale of FIGURE 8 over a wide range.

In the relay unit 68, when the parts are inactive, the first transistor 232 has its base 234 at a potential derived from source 252, and primarily determined by the relative values of resistors 253, 236 and 224, and the potential is negative. Its emitter 238 is held at a plus potential by the adjustable potentiometer 240. Therefore the transistor 232 is conductive. With transistor 232 conducting,

the voltage drop across resistor 256 causes the base 248- of transistor 246 to be of such potential that the collectorto-emitter current is insufficient to operatethe relay 260.

When the potential of point 222 rises in response to the received pulse from generator 61, the first transistor 232 is cutoff, because of a reversal in the polarity of the baseemitter potential.

With transistor 232 cut ofi, the base current of transistor 248 rises, causing a large increase in collectoremitter current, which causes operation of relay 260.

This opens the contact of relay 260, and pulse generator 78, which previously had its armature in position 198 of FIGURE 6 drops to the bottom position. This generates no pulse, but merely conditions the generator so that return to the initial condition will generate a pulse.

After a predetermined time interval, the potential of curve 238 will pass that of the emitter 238, and transistor 232 becomes conductive again. This, as previously described, causes the current to relay 260 to be quickly reduced to the point where the relay cannot hold its contacts open. Closure of the contacts restores power to pulse generator 78 to initiate the burst of sound described previously.

The functioning of timer 63 and relay unit 68 is adjusta'ble by the player in two ways. First, adjustment of resistor 224 deter-mines the overall time scale for the curve 230 of FIGURE 8. Second, the potentiometer 240 determines the precise potential level of the curve 230 at which the reversal occurs, with transistor 232 ceasing to conduct, and subsequently becoming conductive again to complete the cycle and deliver the pulse at the end of the cycle.

The other time delay units 64, 66, 70and 72 may all be duplicates of unit 68.

Timers 63 and 62 may be duplicates, but, as clearly indicated in FIGURE 1, there are three adjustable time delay relay units controlled by timer 63 and only two controlled by timer 62.

Referring again to FIGURE 8 I have designated the time length of a measure of music as M, and indicated by three circles M1, M-2, M3, the precise times at which any desired primary beat M-1, such as a bass drum thump, and any desired off-beats at the beginning of the second and third beats of the measure can be located with precision, with a simple adjustment of one resistor 224 to adjust the time scale for the complete measure, and one potentiometer 240 for each of the later off-beats.

In quite a few types of modern irregular music, it is sometimes desirable to have the automatic accompaniment start at the time a key is released than when it is depressed. In FIGURE 10 the relay 56 has a contact 255 arranged to function when a key is depressed and the current flows from a delivery contact 257, through a stop switch 259 controlled by the operator, into conductor 220. By providing back contacts, 261 opposite contact 255 and 263 opposite contact 257, I provide for reversing the relationship. Switching the stop switch 259 to contact 263 will cause the completion of the cycle and the delivery of the ictus sounds, when the bus 218 no longer receives current for a key switch 214.

DIRECT PLAYER CONTROL In some types of music, considerable irregularity in the unpitched sounds is considered desirable and may be improvised by an expert orchestra. I have indicated a detachable panel 265 in FIGURE 11 which may be conveniently affixed, or hung in place, on the console just in front of the manual 14. This carries a series of push buttons- 262 and adjustment slides 263 and the leads from the push buttons and slides are united in a cable 264 which may extend over to deliver activating potential to any one or more selected pulse generators 60, 61, 74, 76, 7'8, and

82, or to timers 62 and 63. This enables the player, by

MULTIPLE KEY TRIGGERING Referring to FIGURES 1 and 12, the switch 268 permits the player to substitute a relay 266 for the relay 54. The potential of source 216 reaches keys 214 through resistors 215, and bus 218 is connected to ground through a resistor 272. The closing or opening of any key switch 214 will change the potential of point 270 on bus 218. Each such change will cause a momentary current to flow through resistor 272, capacitor 274,- base 278 of the transistor 276 and emitter 280. When this impulse is in the direction to render the transistor conductive, power source 284 will operate relay 286 and pulse generator 60 will be activated to deliver a pulse. This will happen Whenever a key is operated, whether or not other keys are functioning at the same time. To reverse the timing of the operation, so that the player can have the pulse generator function either when a key is depressed or when a key is released, the' power source 216 is provided with a conventional reversing switch 289.

INACTIVE NOISE GENERATORS FIGURE 13 shows a diode type noise generator similar to that shown in FIGURE 3, but the diode and the load resistor have been reversed. Resistor 384 corresponds to resistor 88 of FIGURE 2 and diode 306 corresponds to diode 84 of FIGURE 2. Capacitor 90 delivers noise 9 generated by the diode 306 to the output terminal 92. An additional capacitor 308 is connected between ground and terminal 186. If a pulse of voltage is supplied to terminal 186 the noise generator will begin to operate and to supply a random noise signal to terminal 92, and at the same time capacitor 308 will charge. After the pulse is over the noise will continue at a gradually diminishing rate until capacitor 308 is fully discharged. There is thus provided a normally inactive noise generator that can be turned on in response to a pulse, and that will have desirable envelope characteristics. This modified noise generator can be substituted in place of any one or more of the envelope controls 22, 24, 26, 28 and 30, and when used for all of them would eliminate the need for the continuously operating random noise generator 19.

FIGURE 14 indicates an alternative generator for producing certain types of semi-pitched sound. If a pulse of voltage is delivered to terminal 186, a current will flow through resistor 316 and through inductor 312. Connected across inductor 312 is a capacitor 314, and these two parts form a resonant circuit. The pulse causes the resonant circuit to oscillate and thereby produce a train of damped waves at the resonant frequency. Depending on the constants of inductor 312 and capacitor 314 this will sound like a castanet, cocoanut, Chinese block, etc. The signal is coupled to the output terminal 92 by resistor 318 and capacitor 90. This circuit also can be used to replace any of the envelope controls 22, etc., and when so used replaces also the generator 19. With a pulse generator substantially according to FIGURE 6 there will be a single pulse. To secure a more complete duplication of the multiple clicks of a castanet, the magnetic washer 200 of FIGURE 6 may be omitted or removed, and the contacts 188 and 186 of FIGURE 6 will be closed several times in rapid succession as the plate 194 oscillates before coming to rest in position 198.

ALTERNATIVE INITIATING AND TIMING Referring to FIGURES 15, 16, and 17, the supports 322 and 324 are two square parallel guide rods located below the shelf 265 (see FIG. 11). The rectangle 326 indicates a suitable sound generator such as that of FIG- URE 13 or that of FIGURE 14, or any of the pulse generators 60, 61, 74, 76, 78, 80 and 82.

A series of small slides, of which three are illustrated at 328, 330, and 332, may be adjusted to desired positions on the far rod 322, as by engaging them with the finger tips, and fastened in adjusted position, as by set screws 333. Each slide carries an inclined blade 334 integral with the slide and of conducting material. An insulating facing 336, illustrated in FIGURE 17 only, is aifixed to one side of each blade.

On the near guide rod 324, I provide a single, longer slide 338, which supports a block 340. The block 340 is vertically adjustable, as by means of an adjustment screw 342. From the block 340, a thin, flexible conductor finger 344 extends across toward the guide rod 322. Movement of slide 330 will carry the finger 344 in a path obstructed by each of the blades 334.

As clearly indicated in FIGURE 17, the finger 344 may move to the right in a straight line until its free end strikes the blade 334. Further movement will slide it up to the top of the blade and over the blade as indicated by arrows in FIGURE 17. On return of the slide to initial position the finger will encounter the insulating facing 336 and slide down and under the edge of the blade without establishing electric contact with the blade.

The momentary electric contact established by the finger 344 may complete a circuit for activating the unit 326. This is indicated in FIGURE 16 by a potential source 346, and a circuit through the unit 326, slide 332, blade 334, finger 344, block 346, and slide 338, back to ground at 348. Moving the block 340 up to raise the 1O finger 344 to the level of the dotted line 345 in FIGURE 17 will shorten the space between points 226, and 228, in the curve of FIGURE 8.

Means are provided for enabling the player to move the slide 338, while leaving his hands free for ordinary playing. The yoke 350 is pivoted at 352 and has side arms 354 spaced to lie on either side of the knee of a player seated on bench 18. A heel 356 abuts the slide 338 to hold the yoke in the full line, operative position of FIGURE 16, but the yoke may be swung up out of the Way when not in use, as indicated in dotted lines.

It will be obvious that a single blade 334 may be used to give knee control of pulse generator 60, or 61, or both, or that a series of blades can control pulse generators 74, 76, 78, or 82 or any other desired instrumentality. In the first instance, the automatic timed sequence of sounds is started by the player and runs its course without further attention. In the second instance a skillful operator can vary the timing of the different controlled units to produce a variety of sequences from measure to measure.

Others may readily adapt the invention for use under various conditions of service by employing one or more of the novel features disclosed, or equivalents thereof.

For instance the initiating and timing apparatus might be employed to control sounds produced by generating means other than those disclosed. For example, actual acoustic instruments or recorded sounds could be employed.

Also, while the invention has been described as being used in connection with an organ, it is apparent that it could be used with other instruments, such as the piano, or it could be used in connection with an orchestra, whereby the instrument could replace the conventional drum and trap section.

As at present advised with respect to the apparent scope of my invention, I desire to claim the following subject matter:

1. A musical instrument having a set of playing keys, one for each consecutive semi-tone of the musical scale over a predetermined range; means selectively controlled by said keys for causing the sounding of the various semitones selected by the player; each key being movable to and fro between an upper, released position in which no sound results, and a lower, depressed, playing condition in which the appropriate pitched sound results; an additional source of relatively unpitched sound; and means operatively connected to each of said keys and to said unpitched source, for causing the delivery of a burst of unpitched sound, at a predetermined time with respect to the instant when said key is released.

2. A combination according to claim 1 in combination with alternative connections for delivering timed unpitched sound at predetermined times with respect to the instant when said key is depressed to its lower, playing position; and stop means accessible to the player for rendering said connections operative selectively.

3. A musical instrument having a set of playing keys, one for each consecutive semi-tone of the musical scale over a predetermined range; means selectively controlled by said keys for causing the sounding of the various semitones selected by the player; each key being movable to and fro between an upper, released position in which no sound results, and a lower, depressed, playing condition in which the appropriate sound results; automatic control means for delivering a plurality of timed 'bursts of unpitched sound timed with respect to the instant when said key is moved to its depressed condition; and automatic detector means for initiating the operation of said automatic time control means at the instant any key is moved to its depressed condition, regardless of the number of keys already in depressed condition.

4. A combination according to claim 3, in combination with means for reversing the responsiveness of said detector means, to activate said detector means at the instant when any key is released from depressed condition.

References Cited by the Examiner UNITED STATES PATENTS Rienstra 841.26 Koch 841.22 Hane'rt 841.26 Olson et a1. 841.03

12 Schneeberger et a1. 841 Chesson et a1. 317148.5

Freundt 20087 Hogue 317148.5 Markowitz 841.24 Krauss et a1. 841.26 Campbell 841.24 X

GEORGE N. WESTBY, Primary Examiner.

Bauer 20087 10 CARL W. ROBINSON, Examiner. 

1. A MUSICAL INSTRUMENT HAVING A SET OF PLAYING KEYS, ONE FOR EACH CONSECUTIVE SEMI-TONE OF THE MUSICAL SCALE OVER A PREDETERMINED RANGE; MEANS SELECTIVELY CONTROLLED BY SAID KEYS FOR CAUSING THE SOUNDING OF THE VARIOUS SEMITONES SELECTED BY THE PLAYER; EACH KEY BEING MOVABLE TO AND FRO BETWEEN AN UPPER, RELEASED POSITION IN WHICH NO SOUND RESULTS, AND A LOWER, DEPRESSED, PLAYING CONDITION IN WHICH THE APPROPRIATE PITCHED SOUND RESULTS; AN ADDITIONAL SOURCE OF RELATIVELY UNPITCHED SOUND; AND MEANS OPERATIVELY CONNECTED TO EACH OF SAID KEYS AND TO SAID UNPITCHED SOURCE, FOR CAUSING THE DELIVERY OF A BURST OF UNPITCHED SOUND, AT A PREDETERMINED TIME WITH RESPECT TO THE INSTANT WHEN SAID KEY IS RELEASED. 